Problem: What is the least common multiple of 5 and 15? Another way to say this is: $\lcm(5, 15) = {?}$
The least common multiple is the smallest number that is a multiple of 5 and 15. We know that 5 x 15 (or 75) is a common multiple, but is it the least common multiple? Write out the multiples of 15 until we find a number divisible by 5. 15, So, 15 is the least common multiple of 5 and 15.